Supply circuits for radio sets



March 22, 1927.

J. G. ACEVES SUPPLY CIRCUITS FOR RADIO SIB Fund April 29. 1922 I Inventor,

Julius Gourgues Aceves,

army

Patented Mar. 22, 1927.

UNITED STATES PATENT OFFICE.

JULIUS GOURGUES ACEVES, OF NEW YORK. N. Y., ASSIGNOR 'I'O CROCKER-WHEELER COMPANY, OF AMPERE, NEW JERSEY, A CORPORATION OF NEW JERSEY.

SUPPLY CIRCUITS FOR RADIO SETS.

Application filed April 29, 1922. Serial No. 557,348.

' rect current of requisite uniformity and voltages to the several parts of a radio set.

In the accompanying sheet of drawings which forms a part of this .specification, the figure is a diagrammatic representation of one embodiment of the invention in a receiving set.

An antenna 1 is connected to ground through an adjustable condenser 2 and an adjustable inductance coil 3. There are three radio frequency tubes 4, 5, 5, and a detector tube 6 connected in cascade. The grid of the first radio frequency tube 4 is shown directly connected to the antenna cir-' cuit, the grids of the second and third radio frequency tubes 5, 5 are each connected to the plates of the preceding radio frequency tube inductively through an amplifying transformer with a primary coil 7 and a secondary coil 8. The invention is not limited to any particular number of radio frequency tubes, nor is the invention limited to a single detector tube. The grid of the detector tube is connected to the plate of the last radio frequency tube in cascade inductively through an amplifying transformer with a primary coil 9 and a secondary coil 10. A telephone receiver 11 is con nected to the plate of the detector tube and is shunted by a condenser 12.

Leads 13, 13 are a source of alternating current, for example, 110 volts at sixty cycles, and connect to a primary coil 14. of a transformer with three secondary coils of which one of the transformer coils 15 is connected to the filaments of the radio fre-' quency tubes and the detector tube. Two secondary coils 16, 17 are conhecteflto two rectifier-s 18, .18, the former in a circuit with the filaments and each end of the latter to one of the plates of the rectifiers. From the middle point of one of the secondary coils connected with the rectifier tubes is a circuit through a filter for sup: pressing the alternating components, which consists of a series of sections with choke of the same sign. Bus-bars 24, 25 are led from the terminals of the series of resistances and between them there will be a difference of potential equal to the "oltages of the direct current generated, for example, 125 volts. Bus-bars 26, 27 are led from in termediate points of the series of resistances and the latter is grounded, and the resistances are so proportioned that bus-bar 24: will be 122 volts positive, that bus-bar 26 will be 3 volts positive and bus-bar 25 will be 3 volts negative, all with respect to the grounded bus-bar.

The primary coils of the transformers which connect the radio frequency tubes are connected to the bus-bar 24 and the far end of the filter. The secondary coils of the transformers which connect the amplifying tubes are connected to the bus-bar 25 on which there is a negative potential of three volts with respect to the filaments. The secondary coil of the transformer between the last of the amplifying tubes and the detector tube is connected to the bus-bar 26. on which. there is a positive potential of three volts with respect to the filaments, and the other end of this secondary coil is connected to the grid of the detector tube through a leak resistance 28 shunted by a condenser 29 for the rectification of the si nals. The filaments of the amplifyin tu )es and of the detector tube, are connecte to two'bus-bars 30,- 31 which lead from the ends of the secondary coil 15 and the middle point of this secondary coil is grounded so that the filaments will have an average zero potential.

The connection of the antenna circuit to ground is through the resistance 23 and a condenser 32 in parallel withthe r'esistance.

7 negative with respect to the filaments of these tubes which may be about one-fortieth of the platevoltage; but for rectification the grid must have a plus voltage with respect to the filament, and therefore the grid of-tube 6 must carry a positive charge with respect to its filament, which is customarily about one-fortieth of the plate voltage.

To this end the system is arranged as hereinafter explained so that the voltages across the bus-bars are as follows: between 24 and 27, for example, 122 volts; between 25 and 27 minus 3 volts; between 26 and 27 plus 3 volts. The voltage between 31) and 31 is whatever is necessary and convenient to light the filament with a current of low voltage and hight amperage.

The dillerence of voltage impressed upon the filaments is determined by the number of turns in the secondary coil 15, and the middle point of this coil is grounded. use with commercial tubes this coil should develop about six volts.

The secondary coil 16 of the transformer will supply about seven volts to light the filaments of the rectifiers. Secondary coil 17 is a high voltage winding. From its two halves in opposite phase, alternating cur rent is carried to the plates of the two rectifiers with the result that a pulsating electromotive force is carried to the filter by which it is converted into direct current potential. The circuit of the direct current is through the coils or resistancesof the filter and the resistances 21, 22, 23 back to the middle point of secondary coil 17.

For

In ordinary usage bus-bar 25 should have a voltage of about minus 3 volts to which it charges the grids of the amplifier tubes 4, 5, 5; and bus-bar 26 has a voltage of about plus 3 volts to which it charges the grid of the detector tube 6.

An electrical engineer will easily determine the resistances necessary to secure the object set forth in any particular apparatus connected up as herein indicated.

Where a set is so connected a slight but not seriously disturbing hum of a frequency of 120 cycles is heard with the telephone close to the ear, due to the asymmetrical characteristics of the vacuum tubes and to the shift of thermionic current from one end of the filament to the other as the voltages alternate at the rate of sixty per second. From theoretical considerations confirmed by experiment it is found that the disturbance which causes the hum is proportional to the square of the filament voltage. For this reason resistance o'liilainents of the amplifying and detector tubes should be as low as practicable if an audio-frequei'icy. amplifier is desired. For such use tubes should be operated with oas low frequency as practicable.

What I claim and desire to secure by Letters Patent of the United States, is

In a radio set, the con'ibinatiou of an ampifying tube, means for heating the filament of the tube, a connecting circuit, a source of direct-current energy in separate circuits from the circuit for heating the filament having its positive end connected to the plate and its negative end connected to the grid of the tube, a resistance connected between the two ends of the directcurrent source, and a conductive connection between an intermediate point of the resist ance and the filament circuitywhereby the grid is made more negative than the negative end of the filament.

JULIUS GOURGUES ACEVES. 

